1. Field of the Invention
The present invention relates to an electrical switch.
2. Background Art
Electrical switches are used in many different types of electrical and mechanical-electrical devices, including devices and systems within vehicles. With an ever increasing need to keep the cost of materials and production down, even relatively inexpensive items, such as electrical switches, are being targeted for cost savings. For example, reducing the total number of pieces in a switch, or making it easier to assemble, are two ways in which the overall cost of the switch may be reduced. One of the issues faced by any designer is the problem of determining tolerances for mating parts. Tolerances must be tight enough such that mating parts function properly together, while at the same time, not so tight that manufacturing costs are prohibitive. Moreover, the greater the number of parts, the greater the potential for tolerance stack-up problems.
In the case of electrical switches, it is important that the electrical contacts within the switch will properly engage each other to ensure completion of an electrical circuit. One way to help ensure that the electrical contacts form a good electrical connection is to provide a spring element against one of the contacts to force it against the other contact. One such switch is described in U.S. Pat. No. 4,424,424 issued to Hollenbeck Jr. on Jan. 3, 1984. Hollenbeck Jr. describes a boat battery selector switch which includes a rotary contact which is maintained in compressive contact with other contacts in the switch via a washer and coil spring. One limitation of the switch described in Hollenbeck Jr. is that the spring is in direct contact with the electrical contact itself. This means that any current flowing through the contacts also flows through the spring. The spring is also in contact with a knob utilized by an operator of the switch. Another limitation is that the knob is attached to the switch via a threaded fastener and washer, which requires a cumbersome and time-consuming assembly process. In addition, the rotary contact slides over a portion of the knob, such that even if the coil spring were isolated from the contacts, the knob would still be subject to whatever current flowed through the contacts.
Therefore, it would be desirable to have an electrical switch that was easily assembled such that threaded fasteners were not required to attach the knob, and tolerance stack-up issues were reduced or eliminated through the use of appropriate contact carriers and/or biasing members to maintain an electrical connection between the contact elements of the switch, without requiring unreasonably tight tolerances. It would further be desirable to have a switch in which such biasing elements and the electrical contacts were all electrically insulated from the knob.